This invention relates to a first flush rainwater diverter and collection system, that is, a system for separating and storing an initial flow of normally contaminated rainwater flowing from a catchment region, such as the roof of a building, to a storage region, such as a large capacity tank. The invention is a further development of the invention described in Australian Patent No. 692835.
In the aforementioned patent, there is disclosed a rainwater diverter comprising a T-piece with associated rainwater fall pipe. The T-piece is adapted for connection in the rainwater flow path to intercept the flow of rainwater flowing into a downpipe or directly to a storage or usage area. The fall pipe incorporates a ball-float which seals on a seat when the fall pipe is at least partly full of water, an outlet which limits the rate of flow from the fall pipe in comparison with the maximum flow of rainwater which can enter the fall pipe by way of the T-piece connection, and means enabling solid contaminants to be removed from the fall pipe.
Such a diverter system has been shown by studies conducted by the University of Sydney to be very effective for separating the initial flow of contaminated rainwater from the rainwater flow path.
In many instances, it is desirable to retain the contaminated diverted rainwater for other uses, for instance for application to a domestic garden or the like. This has lead to a modification of the fall pipe in the above-mentioned invention whereby it opens directly into a secondary storage chamber and the outlet is relocated to a suitable position, usually in the base of the secondary storage container. For above ground systems, the outlet typically has a control valve which allows a pre-set flow to continuously drain off and when the rain stops the chamber empties. For underground systems, an automatic sump pump is provided that will typically operate a sprinkler system, or pump directly to a waste drain at a preset time after rain. Both systems effectively operate to completely empty the secondary storage chamber after a set period of time. This can result in a wastage of water. There has consequently been consumer demand for a system which will store the diverted rainwater for later use.